Some of the sentences will be served at the same time, making a total of five years and nine months.

Harris is likely to serve half of the sentence in prison and was told he would not have to pay compensation to his victims. However, the judge said he could have to pay the costs of the prosecution.

A spokeswoman for the Attorney General's Office did not say who had referred the sentence as being "unduly lenient" but said it "only takes one person to trigger the process".

The sentence must be considered within 28 days for possible referral to the Court of Appeal, the spokeswoman added.

Harris was prosecuted based on the law at the time of his offences, when the maximum sentence for indecent assault was two years in prison, or five years for victims under 13.

Two of his victims were in court for the sentencing, which saw members of the press and public fill the public gallery and watch from an overspill court via a video feed.

Harris's daughter Bindi was with him in court but his wife Alwen, who has been consistently present throughout the trial, did not attend.

In court

Jane Peel, BBC News correspondent

The queue outside court two began to form at 07:45 BST - more than two hours before the hearing was due to begin.

Rolf Harris had started his final journey to Southwark in a boat from his house on the Thames, in Bray, Berkshire, but he arrived as usual in a car.

His daughter Bindi was with him but there was no sign of his frail wife, Alwen.

Perhaps in contrast to his mood, he wore a jazzy, multi-coloured tie and a light grey suit.

He had brought with him a similarly bright suitcase with a stripy design. Harris knew he would be going to prison. The only question was for how long.

He had been allowed to stay seated, but was told to stand as Mr Justice Sweeney announced that he would be jailed for five years and nine months.

There was no visible reaction from him or his relatives who were in court as he was led to the cells by two dock security officers.

Peter Watt, of the NSPCC, said: "It sends a message that no-one is untouchable and justice can come at any time."

Alan Collins, of law firm Slater and Gordon, told the BBC his firm had been contacted in "recent days" by people making new allegations against Harris.

He said the calls had come from both the UK and overseas, and lawyers would meet the complainants in the coming days.

Earlier, the court heard impact statements from the four victims, including from the childhood friend of Harris's daughter.

Reading out the statement, prosecutor Esther Schutzer-Weissman said the abuse had "haunted" the victim and left her feeling "dirty, grubby and disgusting".

The statement from the victim who had been seven or eight said the abuse had taken away her "childhood innocence".

Harris indecently assaulted a waitress at a charity event in Cambridge when she was aged 13 or 14, who said the star had "treated me like a toy".

One woman told the BBC she met Harris when she was 18 and he was "very kind, very nice" - but then "sexually abused" her.

The woman, who cannot be named for legal reasons, gave evidence in the trial but the attack in Malta was not the subject of a prosecution because at the time of the incident the offence was outside the jurisdiction of a UK court.

She said Harris led her into a room to show her his artworks.

"He closed the door and then he pushed me up against the wall," she said.

"It was quite intimate, it was forceful and it was scary... I don't know how long it took to be quite honest but I couldn't get away.

"And then he suddenly just stopped, he hugged me and said he was sorry."

She said she had thought she was going to be raped, but she did not report it because she did not think anyone would take her seriously.